Cohesion and Adhesion

Front

Hydrology Noun

---

[hy-drol-uh-jee]

Back

Hydrology

---

The scientific study of the properties, distribution, and effects of water on the Earth's surface, in the soil, and atmosphere.

---

Example: This diagram shows how hydrologists measure a river's width, depth, and velocity, which are key factors in studying the movement of water.

Front

Polarity Noun

---

[poh-lar-i-tee]

Back

Polarity

---

The property of a molecule having an uneven distribution of electrical charge, resulting in partially positive and negative ends.

---

Example: This diagram shows a water molecule (H2O) has an uneven electrical charge. The oxygen end is slightly negative (δ-) and the hydrogen ends are slightly positive (δ+).

Front

Universal Solvent Noun

---

[yoo-ni-vur-suhl sol-vuhnt]

Back

Universal Solvent

---

A substance, particularly water, that has the ability to dissolve a very wide range of other substances.

---

Example: This diagram shows how polar water molecules surround and separate the positive (cation) and negative (anion) parts of a substance, causing it to dissolve.

Front

Cohesion Noun

---

[koh-hee-zhuhn]

Back

Cohesion

---

The intermolecular force of attraction between molecules of the same substance, causing them to stick together tightly.

---

Example: This diagram shows water molecules sticking to each other through hydrogen bonds, which is the force responsible for cohesion.

Front

Adhesion Noun

---

[ad-hee-zhuhn]

Back

Adhesion

---

The force of attraction between molecules of different substances, causing them to stick to various surfaces.

---

Example: This diagram shows water climbing up a narrow glass tube because the water molecules are more attracted to the glass (adhesion) than to each other.

Front

Surface Tension Noun

---

[sur-fis ten-shuhn]

Back

Surface Tension

---

The property of a liquid's surface that makes it difficult to stretch or break due to strong cohesive forces.

---

Example: This diagram shows that liquid molecules inside are pulled in all directions by cohesion, while surface molecules are pulled only inwards, creating a tight 'skin' called surface tension.

Front

Capillary Action Noun

---

[kap-uh-ler-ee ak-shuhn]

Back

Capillary Action

---

The ability of a liquid to flow in narrow spaces without assistance, often in opposition to external forces like gravity.

---

Example: This diagram shows capillary action, where water is pulled up a narrow tube because the attraction between water and the tube (adhesion) is strong.

Front

Transpiration Noun

---

[tran-spuh-rey-shuhn]

Back

Transpiration

---

The biological process where plants absorb water through roots and then release water vapor from pores in their leaves.

---

Example: This diagram shows how water is absorbed by a plant's roots, travels up the stem, and is released as water vapor from the leaves.

Front

Meniscus Noun

---

[muh-nis-kuhs]

Back

Meniscus

---

The curved upper surface of a liquid in a container, caused by the interplay of adhesion and surface tension.

---

Example: This diagram shows the two types of meniscus: a lower (concave) meniscus where liquid adheres to the container, and an upper (convex) meniscus where liquid coheres to itself.